Structure and Hydrogen Adsorption Properties of SBA-15 Doped with Pd Nanoparticles

Hydrogen adsorption properties of Pd-doped Santa Barbara amorphous No. 15 (Pd-SBA-15) were investigated and the results were compared with pure SBA-15 ones in terms of change of its structure and Pd concentration. Pd-SBA-15 samples were prepared by a hydrothermal reaction, using mixture of PEO₂₀PPO₇₀PEO₂₀ (P123) and tetraethyl orthosilicate (TEOS). For the doping of Pd on SBA-15, PdCl₂ solution was added into the mixture of P123 and TEOS, and the solution was annealed at 80 °C for 2 hours under 800 Torr of hydrogen atmosphere. According to the X-ray diffraction and transmission electron microscope data, Pd-doped SBA-15 samples form a hexagonal array of mesoporous structure with 20∼30 nm size of Pd particles. Values of specific surface area decreased from 630 to 414 m²/g as increasing the Pd doping level due to the increasing of the volume density. In fact, the volume density increased from 0.103 to 0.276 g/cc as increasing the mass ratio of PdCl₂ to TEOS from 0 to 0.5. For the Pd-doped SBA-15, the amount of adsorbed hydrogen significantly increased from 0.49 to 0.99 wt% as increasing the Pd doping level from 0 to 0.5 demonstrating that Pd doping is an effect method for SBA-15 as a potential use of hydrogen storage application.